The term 'fancy diamond' refers to the categories of diamond, which are more richly colored, their value depending on the intensity of the color. The unique colors of fancy diamonds are naturally caused by 'impurities' in the stone resulting from the pressure that diamond was exposed to during formation. If the said impurities appear in considerable amount, the diamond will be considered 'fancy' and can command a high price, particularly if the color is rare. Nitrogen and boron both cause colors to appear in fancy diamonds, as do irradiation, which determines green diamonds. The color spectrum of fancy diamonds encompasses yellow, green, blue, brown, orange, pink, and red. Brown fancy diamonds are also referred to as 'claret' and the brownish-yellow ones as 'champagne' diamonds. The Gemological Institute of America (GIA) grades fancy diamonds in each color on the basis of 'hues' commencing with 'faint', moving through 'very light', light, and ending with 'vivid fancy', based on the intensity of color. Fancy diamonds are often faceted into unusual, fancy cuts to enhance their natural beauty.